We propose a set of developmental studies of face expertise acquisition from infancy to adolescence. An international team of researchers will advance significantly our on-going research program (R01 HD046526: 2004-2010) to investigate how children's face expertise acquisition is tuned by experience in their unique environments. We will use two research strategies to establish linkages between experiences and face expertise acquisition. First, we will sample infants and children from several countries to capitalize on their naturally occurring experiential differences with faces of different races, genders, ages, and species. Second, we use a training paradigm to experimentally induce different experiences with faces of various categories to infants and children. In contrast to traditional face processing studies that employ static face exemplars, we will test participants with the more naturalistic dynamic facial stimuli. This method should provide a sensitive measure of infants'and children's ability to extract characteristic properties of the face such as its race, gender, age, species, and identity. We will concurrently examine children's recognition and categorization of faces of different races, genders, ages, and species. We will test a general hypothesis that while the human visual system may favor face-like stimuli at birth, much of our face processing ability is acquired through experience with thousands of faces during development. Different degrees of exposure to various categories of faces (race, gender, age, and species) impact on our face expertise acquisition in systematically different ways: With increased experience with one type of face category (e.g., female faces) over another (e.g., male faces), children become better at recognizing the individual faces of the more experienced category (e.g., recognizing individual female faces better than male ones) but better at categorizing the less experienced faces (e.g., categorizing male faces as "male" better than female faces as "female"). This research program will provide much needed information to form a comprehensive picture of the development of face processing abilities and to delineate the role of experience in the formation of face expertise. Our research should facilitate the development of a general theory of face processing in children and adults. The methods we refine for this project can be of use for clinical studies and assessments that involve children with atypical trajectories in the development of face processing including cases of autism and developmental prosopagnosia. Our findings may also provide information about the origin of social biases such as race-, gender-, and age-stereotypes and prejudices, and methods to reduce them. PUBLIC HEALTH RELEVANCE: This research program investigates how typically developing infants and children acquire the ability to classify faces into different categories according to their gender, race, age, and species and the ability to recognize individual faces from within these categories. The results from this research will provide the normative bench mark against which we can evaluate the face processing abilities of children with various developmental and neurological disorders (e.g., autism, William's syndrome, developmental prosopagnosia). The methodologies developed from the program of research will enable clinicians to develop appropriate assessment tools to identify and diagnose infants and children with potential face processing problems. Further, the training method we will test in the present proposed program of research will also allow for the development of evidence-based intervention programs to treat face processing deficits in childhood. Finally, our findings may also provide information about the origin of social biases such as race-, gender-, and age-stereotypes and prejudices, and methods to reduce them.